Yocto

It is not a distribution' but a collection' of tools, templates, methods, for creating embedded linus systems.
The Yocto Project targets customized Linux systems supporting the ARM, MIPS, PowerPCand x86/x86-64 architectures.
A key part of this is the OpenEmbedded build system, which enables developers to create their own Linux distribution specific to their environment.

The Yocto Project and OpenEmbedded Project share maintainership of the main parts ofthe OpenEmbedded build system:- the build engine, BitBake,- and the core metadata, OpenEmbedded-Core.
a reference implementation called Poky, which contains the OpenEmbedded build systemplus a large set of recipes, arranged in a hierarchical system of layers, that can be used asa fully functional template for a customized embedded operating system.
There are several other sub-projects under the proect umbrella which include CROPS, pseudo, the matchbox suite of applications, and many others.
As well as building Linux systems, there is also an ability to generate a toolchain for crosscompilation and a software development kit (SDK) tailored to their own distribution. It ispossible to select which package manage'r format to use (deb, rpm, or ipk).